Method of protecting rotating machine

Claim 1

Apparatus for controlling a machine having a rotating part driven by a motor shaft comprising a vibration sensor for the rotating part for deriving a signal having an amplitude indicative of vibration of the part, a controller responsive to the amplitude vibration sensor for selectively stopping rotation of the shaft, the controller being arranged so that the shaft rotation is (a) stopped in response to the amplitude of the signal having a predetermined amplitude relation at first and second different displaced time instants and (b) not affected by the vibration sensor in response to (i) the amplitude being less than a predetermined value at one of said instants and (ii) the predetermined amplitude relation occurring at only one of said time instants.

Claim 6

A method of controlling a machine having a rotating part driven by a motor shaft comprising sensing vibration of the rotating part, stopping rotation of the part in response to the amplitude of the sensed vibration having a predetermined amplitude relation at a pair of displaced first and second different time instants, and maintaining the rotating speed at a predetermined value in response to the sensed vibration (i) being less than a predetermined value at one of said instants and (ii) the predetermined amplitude relation occurring at only one of said time instants.

Claim 7

A method of controlling a machine having a rotating part driven by a motor shaft comprising sensing vibration of the rotating part, stopping rotation of the part in response to the amplitude of the sensed vibration having a predetermined amplitude relation at a pair of displaced first and second different time instants, and maintaining the rotating speed at a predetermined value in response to the sensed vibration (i) being less than a predetermined value at one of said instants and (ii) the predetermined amplitude relation occurring at only one of said time instants.

Claim 9

A method of protecting a rotating machine including a rotating body connected to and driven by a drive unit via a drive shaft, comprising the steps of: (a) activating the drive unit to rotate the drive shaft and the rotating body, the drive shaft and the rotating body vibrating with a vibrating amplitude while driven by the drive unit; (b) detecting the vibration amplitude of the rotating body or the drive shaft while the rotating body and the drive shaft are rotating; (c) comparing the thus-detected vibration amplitude with at least a first predetermined allowable value and a second predetermined allowable value larger than said first predetermined allowable value; (d) in response to the detected vibration amplitude being initially in a first range between said first and second allowable values, detecting whether the detected vibration amplitude is still in the first range when a first predetermined period of time subsequent to the initial time of the amplitude detection elapses; (e) in response to the detected vibration amplitude being initially greater than said second predetermined allowable value, detecting whether the detected vibration amplitude is still greater than the second allowable value when a second predetermined period of time which is shorter than said first predetermined time period and subsequent to the initial time of the amplitude detection elapses; (f) deactivating the drive unit to stop rotation of the drive shaft and the rotating body in response to said detecting step (d) or (e) indicating the presence of the initially detected vibration amplitude; and (g) continuing activation of the drive unit so the drive shaft and the rotating body continue to rotate in response to the detected vibration amplitude being smaller than said first predetermined allowable value or in response to said detecting step (d) or (e) indicating the absence of the initially detected vibration amplitude.

Claim 10

A method of protecting a rotating machine including a rotating body connected to and driven by a drive unit via a drive shaft, comprising the steps of: (a) activating the drive unit to rotate the drive shaft and the rotating body, the drive shaft and the rotating body vibrating with a vibrating amplitude while driven by the drive unit; (b) detecting the vibration amplitude of the rotating body or the drive shaft while the rotating body and the drive shaft are rotating; (c) comparing the thus-detected vibration amplitude with at least a first predetermined allowable value and a second predetermined allowable value larger than said first predetermined allowable value; (d) in response to the detected vibration amplitude being initially in a first range between said first and second allowable values, detecting whether the detected vibration amplitude is still in the first range when a first predetermined period of time subsequent to the initial time of the amplitude detection elapses; (e) in response to the detected vibration amplitude being initially greater than said second predetermined allowable value, detecting whether the detected vibration amplitude is still greater than the second allowable value when a second predetermined period of time which is shorter than said first predetermined time period and subsequent to the initial time of the amplitude detection elapses; (f) deactivating the drive unit to stop rotation of the drive shaft and the rotating body in response to said detecting step (d) or (e) indicating the presence of the initially detected vibration amplitude; and (g) continuing activation of the drive unit so the drive shaft and the rotating body continue to rotate in response to the detected vibration amplitude being smaller than said first predetermined allowable value or in response to said detecting step (d) or (e) indicating the absence of the initially detected vibration amplitude.

Claim 13

A method of controlling a machine having a rotating part driven by a motor shaft comprising sensing vibration of the rotating part, stopping rotation of the part in response to the amplitude of the sensed vibration having a predetermined amplitude relation at a pair of displaced first and second time instants, and maintaining the rotating speed at a predetermined value in response to the sensed vibration (i) being less than a predetermined value at one of said instants or (ii) the predetermined amplitude relation occurring at only one of said time instants, the predetermined amplitude relation including plural amplitude ranges, different second displaced time instants being associated with each of said amplitude ranges, the displacement of the first and second time instants associated with the amplitude ranges being such that shorter displaced time instants are associated with larger amplitude ranges, a first of the ranges being between A 1 and A 2 , a second of the ranges being between A 2 A 3 and a third range being in excess of A 3 , where A 1 ≦A 2 ≦A 3 , the time displacements (t 1 -t 4 ), (t 1 -t 3 ) and (t 1 -t 2 ) between the first and second time instants being respectively associated with the first, second and third ranges, where (t 1 -t 4 ) ≧(t 1 -t 3 )≧(t 1 -t 2 ).

Claim 14

A method of controlling a machine having a rotating part driven by a motor shaft comprising sensing vibration of the rotating part, stopping rotation of the part in response to the amplitude of the sensed vibration having a predetermined amplitude relation at a pair of displaced first and second time instants, and maintaining the rotating speed at a predetermined value in response to the sensed vibration (i) being less than a predetermined value at one of said instants or (ii) the predetermined amplitude relation occurring at only one of said time instants, the predetermined amplitude relation including plural amplitude ranges, different second displaced time instants being associated with each of said amplitude ranges, the displacement of the first and second time instants associated with the amplitude ranges being such that shorter displaced time instants are associated with larger amplitude ranges, a first of the ranges being between A 1 and A 2 , a second of the ranges being between A 2 A 3 and a third range being in excess of A 3 , where A 1 ≦A 2 ≦A 3 , the time displacements (t 1 -t 4 ), (t 1 -t 3 ) and (t 1 -t 2 ) between the first and second time instants being respectively associated with the first, second and third ranges, where (t 1 -t 4 ) ≧(t 1 -t 3 )≧(t 1 -t 2 ).